Europium-activated barium magnesium silicate phosphors are fluorescent lamp phosphors used in photocopy applications. When excited by 254 nm radiation, this phosphor emits light at a peak wavelength of 398 nm and a bandwidth of 24 nm. Such a phosphor has the general formulation BaMg.sub.2 Si.sub.2 O.sub.7 :Eu and is described in U.S. Pat. No. 3,651,363 to Barry, the disclosure of which is incorporated by reference.
The atomic concentration of the component elements of the prior art phosphor at its particle surfaces can be measured by Electron Spectroscopy for Chemical Analysis (ESCA) and is typically as follows: 2.3% barium, 1.4% europium, 25% magnesium, 15% silicon and the balance oxygen.
Lamps made with the prior art phosphor generally have poor 100-hour performance (maintenance) characteristics.